Conventionally, there are two types of methods for manufacturing low-edge V-belts. One is an angle-cut method and the other is a method in which a vulcanized annular body is cut in square and then ground in V form (SCAM). The former method comprises the steps of: (1) forming a laminated body of belt on an iron cylindrical drum; (2) vulcanizing the belt forming body; (3) cooling the belt forming body; (4) removing the vulcanized and sleeve-like belt forming body from the drum; (5) storing the removed belt forming body; (6) transferring the belt forming body to an expander drum and providing V-form cutting to individual V-belts; (7) siding to grind the side surfaces of each V-belt by winding the V-belt on a pair of pulleys for reducing the eccentricity of the V-belt; (8) inspecting the sided V-belt; and (9) deburring the inspected V-belt.
The latter, alternative method involves the steps of cutting the annular body in square to a predetermined width, turning each belt inside out, and then grinding the side surfaces in V form.
However, the above-described methods are only satisfactorily applicable to manufacturing belts whose size is relatively short (less than 100 inches) and thus present problems when applied to manufacturing relatively long belts (100 inches or more). In the former method it is difficult to make the vulcanized annular body for large width belts perfectly circular because it involves the use of an expander to which the vulcanized annular body must be transferred. Thus, when providing V-form cutting to the vulcanized annular body, the upper width and angles of the belt becomes erratic, thereby requiring an additional step of siding, or grinding the side surfaces of the V-belt. This causes inconveniences of not only producing much scrap but also complicating the manufacturing process.
Although variations in the width and angles of the V-belt are not as noticeable as with the first described method, the process of grinding the V-shaped grooves on a single belt basis by the latter method impairs productivity and may even result in increasing the manufacturing cost. Disclosure of the Invention
The object of the present invention is to provide a method of manufacturing low-edge V-belts, a method which ensures high accuracy in cutting and satisfactory working efficiency by grinding a plurality of V-shaped portions simultaneously on a relatively long, flat-belt-shaped vulcanized annular body wound on two drums, and subsequently cutting the ground V-form portions.
To achieve the above object, present invention includes the steps of forming an unvulcanized belt annular body inside out by winding respective components constituting the elongated portion, tension-resistant portion, and compressed portion of the belt in laminated form on the peripheral surface of a forming drum; vulcanizing the unvulcanized belt annular body to obtain a vulcanized annular body; revolving the vulcanized annular body by winding on a pair of drums including a drive drum and a driven drum to thereby grind V-shaped grooves on the surface of the vulcanized annular body. The grinding wheel has a group of grindstones whose cross-section is V-shaped arranged in pressure contact with the drive or driven drum; causing projections arranged on a positioning member which is capable of gradually increasing the depth of their engagement to engage with the V-shaped grooves; and cutting off the ground V-shaped grooves thereafter.